Wireless communications systems offer a variety of services to subscribers such as interconnect calling, short message service, packet data communications and dispatch communications. Many wireless communications systems facilitate communications between a wireless application server and a client application resident on the wireless subscriber unit. For example, dispatch services (also known as “push-to-talk” or “walkie-talkie” services) are currently offered as an Internet protocol (IP) application served by a dispatch server. Dispatch communication services are commonly implemented as a push-to-talk (PTT) type of service, such as the dispatch call service marketed by Sprint Nextel Corporation under the trade name Direct Connect or the dispatch communication service developed by Qualcomm under the trade name of QChat.
Current systems and methods for dispatch communications rely on a serial procedure for connection of a subscriber device to a target device. PTT communications are initiated by a subscriber first selecting a target subscriber, followed by pressing a so-called “PTT button” on their handheld device. Conventionally, call requests are sent to a base transceiver station and routed to a push-to-talk server which locates a target subscriber and routes the call request to a target BTS. Conventional methods and devices perform a serial operation for establishing a subscriber call, and require substantial setup times for initiating and connecting PTT devices resulting in significant latency time periods for call setup.
The use of activating a target mobile device to a ready state prior to initiating call setup has been suggested by U.S. Patent Application Publication No. 2006/0111134 to Mills. However, this approach requires calling a mobile station and to change to an operational state prior to initiating a call setup. Further this approach requires substantial processing prior to calling a mobile station and operates in a serial manner extending set up time.
Substantial setup times add to the latency of call setup, tie up resources and consume excess power. Thus, there is a need for a dispatch communication system and method for reducing call setup latency.